In watch cases with an independent, detachable back, casing up and uncasing the watch movement is effected without the shaft for setting the time and, possibly, the calendar. This is placed in position after the movement has been introduced into the case, or removed before withdrawing the movement from the case. The fastening of this shaft to the movement, in the first instance, and its release, in the second, are customarily effected by actuating a post which is integral with the pull-out piece and only accessible from the back of the movement. This operation is simple when the back of the case may be removed. In cases having a back cover which is integral with the case band, i.e. in cases where the back and the case band are manufactured in one piece, this operation is, however, no longer possible.